As shown by Barry et al, U.S. Pat. No. 2,474,087, disilanes have been used to make organosilanes by reacting halogenated organic compounds, such as alkyl halides or aryl halides, with halodisilane in the presence of a metallic catalyst. A somewhat similar procedure is shown in U.S. Pat. No. 3,772,347, Atwell et al, employing a halogenated disilane and an organic chloride such as chlorobenzene or butyl chloride to produce the appropriate organohalosilane.
Transition metal catalyzed silylation of activated aromatic substrate with polysilane can sometimes be less predictable. It has been found that the nature of the activating group on the aromatic nucleus can enhance or interfere with the nuclear silylation. For example, as shown by Matsumoto et al., JOMC 85, Cl (1985), nitrochlorobenzene can be readily silylated with disilane. Experience has shown, however, that the silylation of carbonyl substituted aromatic compounds with polysilane is often not feasible, since disilanes are well-known reducing agent for carbonyl groups. For example, conversion of aromatic aldehyde to alcohol is shown by Japanese Patent No. 5942391. Reductive silylation of p-quinone is shown by Matsumoto et al., Chem. Lett. 4 (1982) pp. 533-4. The silylation of certain functionalized aromatic dicarbonyl compounds, such as chlorophthalic anhydride with disilane also is not feasible.
An additional factor in predicting ease of silylation of aromatic substrates with polysilanes is the nature of the monovalent radicals of the polysilane attached to silicon. In some cases, for example, aromatic substrates are more readily silylated with polysilane having monovalent hydrocarbon radicals attached to silicon, such as hexamethyl disilane, than polysilane having one or more functional groups attached to silicon, such as halogen or alkoxy. The preferred monovalent functional groups attached to silicon are methoxy, ethoxy, propoxy, butoxy and pentoxy, or a phenoxy group, and chloro, as well as a mixture thereof.
The present invention is based on the discovery that unlike carbonyl substituted aromatic compounds, such as halogenated aromatic anhydrides, other functionalized aromatic dicarbonyl compounds, such as halogenated aromatic imides, for example, chlorophthalimide, can be readily silylated with polysilanes including polysilanes substituted with functional groups, such as halogen and alkoxy. As a result, the present invention provides for the synthesis of silylaromatic imides in accordance with the following equation: ##STR1## where X is halogen, R is a monovalent radical selected from the class of X, hydrogen, C.sub.(1-8) alkoxy, C.sub.(1-13) hydrocarbon and substituted C.sub.(1-13) hydrocarbon, R.sup.1 is selected from R, --O-- and --S--, and when R.sup.1 is --O-- or --S-- or a mixture thereof, R.sup.1 can form ##STR2## connecting groups, R.sup.2 is a trivalent C.sub.(6-13) aromatic organic radical, R.sup.3 is selected from C.sub.(1-13) monovalent hydrocarbon and C.sub.(1-13) monovalent hydrocarbon radicals substituted with neutral radicals, and n is an integer having a value of from 1 to 50 inclusive.